1. Field of the Disclosure
This disclosure relates in general to assemblies for gripping polished rods in hydrocarbon production operations, and in particular to interchangeable adapters with gripping surfaces for use in such assemblies.
2. Description of Related Art
During some hydrocarbon production operations, a drive can be used to rotate a polished rod that extends into a subterranean well. The rotating polished rod in turn drives a pump that provides lift to fluids that are within the subterranean well and can be used to force such fluids to the surface and be produced into a flow line. Such a production system can be used, for example, with a steam assisted gravity drainage process, which is undertaken at high temperatures.
In order to perform service on the production system that requires the polished rod to be locked in a non-rotating condition, a gripping surface of a piston ram can engage the polished rod. The piston rams can be part of a lock-out device, or can part of a blowout preventer (BOP) that has one or more sets of rams with various functions. When in the closed position the piston rams can clamp around the polished rod and secure the rod string. In certain embodiments, the piston rams can also seal off the well bore. The sealing function and gripping function can be carried out by a single set of rams. The clamping action of the piston rams reduces environmental and safety risks while performing services on the production system.
The polished rods used to drive the pump can have different diameters, depending on the make, model, and size of pump that is being run downhole. Therefore, the piston ram gripping surface and polished rod clamp gripping surface will both need to be properly sized to fully engage and grip the polished rod of the specific size used in the particular production operation. The gripping surfaces must provide a sufficient grip to both support the weight of the rod string and pump, as well as resist any rotation or torque applied to the polished rod. If the pump is replaced with a new pump that requires a different sized polished rod, the gripping surfaces for the polished rod clamp and the piston ram may not properly grip the new polished rod and will need to be resized. There may also be times when the gripping surfaces of the polished rod clamp and the piston ram become worn and need to be replaced.